T1 Sonar systems provide a small, but clear intelligence circle that will reveal any naval units within its range. The T1 Sonar system is almost the same acrossed the board. The only difference is HP UEF 600, Cybran 400, Aeon/Seraphim 500. Other than that they are all the same. They all upgrade into their tech 2 counterparts giving them a better intelligence range and more health. Because they are so cheap you should have one ASAP on all water maps. they can be used to detect underwater ACUs and that is often what happens early game on maps like The wilderness when the ACU has taken heavy damage.